Citrix Virtual Apps and Desktops

Adaptive transport

Adaptive Transport is a mechanism in Citrix Virtual Apps and Desktops that allows establishing connections for HDX sessions using a preferred transport protocol while providing a fallback to TCP if connectivity with the preferred protocol is unavailable.

The following transport protocols are supported:

  • Enlightened Data Transport (EDT)
  • Transmission Control Protocol (TCP)

Configuration

Adaptive Transport is enabled by default. You can configure Adaptive Transport to operate in the following modes:

  • Preferred: (Default) The client attempts to connect with the preferred protocol and falls back to TCP if connectivity with the preferred protocol is unavailable.
  • Diagnostic mode: The client only attempts to connect using the preferred protocol. Fall back to TCP is disabled.
  • Off: The client only attempts to connect using TCP.

How it works

When Adaptive Transport is set to Preferred, the client attempts to connect to the session with both the preferred protocol and TCP in parallel. This allows optimizing the connection time if it’s not possible to connect with the preferred protocol and the client must fall back to using TCP. If the connection is established using TCP, the client attempts to connect with the preferred protocol in the background every five minutes.

When Adaptive Transport is set to Diagnostic mode, the client connects to the session only with the preferred protocol. If the client is unable to establish a connection using the preferred protocol, it doesn’t fall back to using TCP, and the connection fails.

When Adaptive Transport is set to Off, Adaptive Transport is disabled, and the client connects to the session using TCP only.

Network stack

Adaptive transport

System requirements

The following are the requirements for using Adaptive Transport and EDT:

  • Control plane
    • Citrix DaaS (formerly Citrix Virtual Apps and Desktops service)
    • Citrix Virtual Apps and Desktops 1912 or later
  • Virtual Delivery Agent
    • Version 1912 or later (2308 or later recommended)
    • Version 2012 is the minimum required for using EDT with Citrix Gateway Service
  • Citrix Workspace app
    • Windows: version 2209 or later
    • Linux: version 2211 or later
    • Mac: version 2210 or later
    • iOS: latest version available in the Apple App Store
    • Android: latest version available in Google Play
  • Citrix NetScaler Gateway
    • 14.1.12.30 or later (recommended)
    • 13.1.17.42 or later

Network requirements

The following sections are the network requirements for using EDT with Adaptive Transport:

Session hosts

If your session hosts have a firewall such as Windows Defender Firewall, you must allow the following inbound traffic for internal connections.

Description Source Protocol Port
Internal connection - Session Reliability enabled Client

UDP

2598
Internal connection - Session Reliability disabled 1494
Internal connection - HDX Direct or SSL VDA 443

Note:

The VDA installer adds the appropriate inbound rules to the Windows Defender Firewall. If you use a different firewall, you must add the rules above.

Internal network

The following table depicts the firewall rules required for using EDT in your network:

Description Protocol Source Destination Destination port
Direct internal connection - Session Reliability enabled UDP



Client network

VDA network



2598
Direct internal connection - Session Reliability disabled 1494
Direct internal connection - HDX Direct or VDA SSL 443
NetScaler Gateway NetScaler SNIP
2598
NetScaler Gateway - VDA SSL 443

Note:

If you are using Citrix Gateway Service, you must enable Rendezvous to use EDT as your transport protocol. See the Rendezvous documentation for system and network requirements.

Adaptive transport